Anti-sag underarm for horizontal boring, drilling and milling machines and the like



Jan. 4, 1966 G. H. JONES ETAL 3, ,0

ANTI-SAG UNDERARM FOR HORIZONTAL BORING, DRILLING AND MILLING MACHINES AND THE LIKE Filed Feb. 20 1963 4 Sheets-Sheet 1 Ml I I 1 \F M /6 I (F 1 c9 'I T (D x- (0 /i4 s 30 I i i a i Z I I "I F,

' i N Z "1H /4 III II I 93 5 5 5 90 INVENTORS. L I szfrwamfixiifi I BY 3,22 7,047 G, DRILLING IKE Jan. 4, 1966 G. H. JONES ETAL ANTI-SAG UNDERARM FOR HORIZONTAL BORIN AND MILLING MACHINES AND THE L 4 Sheets-Sheet 2 Filed Feb. 20, 1963 1966 G. H. JONES ETAL 3, 7,

ANTI-SAG UNDERARM FOR HQRIZONTAL BORING, DRILLING AND MILLING MACHINES AND THE LIKE Filed Feb. 20, 1963 4 Sheets-Sheet 5 3; 6 '7 9): i INVENTORS.

zu fmj, wram 3,227,047 G, DRILLI LIKE 4 Sheets-Sheet 4 FOR HORIZONTAL BORIN ARM AND MILLING MACHINES AND THE G. H. JONES ETAL SAG UNDER ANTI Jan. 4, 1966 Filed Feb. 20, 1963 United States Patent ANTI-SAG UNDERARM FOR HORIZONTAL BORING, DRILLING AND MILLING MA- CHINES AND THE LIKE Gordon H. Jones, Fond du Lac, Wis., and Fritz Schultheiss, London, England, assignors to Giddings & Lewis Machine Tool Company, Fond du Lac, Wis., a corporation of Wisconsin Filed Feb. 20, 1963, Ser. No. 259,966

16 Claims. (CI. 90-16) The present invention relates to the field of machine tools and more specifically to a novel underarm support mechanism finding particular but not exclusive utility in machine tools of the type known as horizontal boring, drilling and milling machines.

Machines of this type frequently include a headstock having an extensible power driven spindle, together with a sliding support member known as an underarm. The latter is translatable parallel to and in synchronism with the spindle and serves as an outboard support for the tools, fixtures or attachments utilized with the headstock. Such machines are, for example, illustrated and described in United States Patents Nos. 2,890,629 and 2,984,- 159, issued June 16, 1959, and May 16, 1961, respectively, on the applications of Garner H. Schurger et al.

In other machine configurations, the sliding support member may be utilized as a tool carrying ram for planing or shaping operations, independently of a spindle. In still other machines, the sliding support may actually house a spindle, the latter being substantially concentric therewith. The term underarm, as used herein, is intended to apply to a variety of such sliding support members, whether or not they are associated with, or under, a spindle.

An underarm is usually designed as a relatively stiff, boxlike structure of substantial cross-sectional area but, upon extension from the headstock or other support, it behaves as a cantilever beam and undergoes a certain amount of deflection which tends to impair machining accuracy. The deflection increases in proportion to the amount of extension of the underarm from the headstock or support and which extension may, for example, vary from zero to 60 inches. Underarm deflection results from the weight of the underarm per unit length and from external loads due to the weight of the tool, fixture or attachment mounted at the outboard end of the underarm. Still another factor contributing to underarm deflection is misalignment of one or more machine frame members, or the guideways connecting such members, due to the weight, or disposition of the weight, of the underarm.

With the foregoing in mind, it is an object of the present invention to provide an underarm support mechanism for a machine tool which will compensate fully for underarm deflection due to the weight of the underarm itself, or to be weight of the tool, fixture or attachment mounted at the outboard end of the underarm, or to misalignment of one or more of the associated machine frame members.

Another object of the invention is to provide an underarm support mechanism of the character set forth and adapted to compensate automatically for underarm deflection continuously as the underarm is extended or retracted and regardless of the amount of extension within the range of underarm movement so that the underarm will remain essentially horizontal.

A further object is to provide an underarm support mechanism of the foregoing type wherein the compensation for underarm deflection may be selectively adjusted to correspond with various tools, fixtures or attachments mounted on the underarm.

3,227,047 Patented Jan. 4, 1966 ice Still another object of the invention is. to provide an underarm support mechanism of the character set forthand which utilizes a novel arrangement for creating internal counterbending forces of proper magnitude to prevent deflection of the underarm throughout its range of movement.

Other objects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the appended drawings, where- FIGURE 1 is a perspective view of an illustrative horizontal boring, drilling and milling machine embodying the present invention.

FIG. 2 is an enlarged fragmentary perspective view of the underarm support mechanism of the machine shown in FIG. 1.

FIG. 2A is an enlarged fragmentary perspective view detailing a portion of the adjusting mechanism within the underarm.

FIG. 3 is a further enlarged fragmentary sectional view taken vertically through the inboard portion-of the underarm and headstock of the machine shown in FIG. 1.

FIGS. 4A and 4B are further enlarged fragmentary vertical sectional views taken longitudinally through the inboard end portion of the underarm.

FIG. 5 is a transverse sectional view of the underarm taken in the plane of the line 5-5 of FIG. 4A.

FIG. 6 is a transverse sectional view taken in the plane of the line 6--6 of FIG. 4B.

FIG. 7 is an enlarged detailed elevational view'of an adjusting cam and index dial at the outboard end of the underarm, as shown in FIG. 4B.

FIG. 8 is a schematic representation of the underarm in two of its possible extended positions.

While the invention is susceptible of various modifications and alternative constructions, an illustrative embodiment has been shown in the drawings and. will be described below in considerable detail. It should be understood, however, that there is no intention to limit the invention to the specific form disclosed, but, on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as expressed in the appended claims.

General organization of the machine Referring more specifically to the drawings and with particularity to FIGURE 1, the present invention is there exemplified in a heavy duty horizontal boring, drilling and milling machine 10 of a general configuration wellknown to those skilled in the art. The machine 10 in this instance comprises a bed 12 having three parallel ways 14 longitudinally formed thereon. A vertical. column 16, including a column base, is disposed for, move: ment on the ways 14 longitudinally of the bed. The

column supports a headstock 18 disposed for vertical translation on ways 20 formed on the vertical column 16. Because of the size of the machine 10, a control. station, including a platform 22, is secured to. the casing 24 of the headstock so as to permit the operator to ride with the headstock. The headstock 18 supports a horizontal spindle 26 which may be rotated and translated on an axis parallel to the top of the bed 12 by extending or retracting the spindle into and out of the headstock 18. The above arrangement comprises. the working end of the machine, which performs operations on a workpiece located adjacent the spindle on an appropriate work support (not shown).

The machine 10 is provided with an extensible underarm St) slidably housed in the headstock 18 below and parallel to the spindle 26. The underarm and the spindle are movable axially in unison to meet the requirements of any given job, the underarm providing a running support for the spindle and its associated tools, fixtures or attachments. In the present instance, a s indle support 32 is mounted at, the outboard end of the underarm and receives and supports the end of the spindle 26. The latter includes suitable means for mounting a tool and the construction of the support 32 may be such as to permit the spindle and tool to be projected axially beyond it.

In keeping with the present invention, the machine and underarm embody a novel anti-sag arrangement which is adapted to compensate fully for deflection of the underarm throughout its range of movement. The foregoing is accomplished through a mechanism adapted to develop appropriate internal forces of suificient magnitude to resist deflection of the underarm due to one or more of the following factors: (1) its own weight; (2) the weight of the tool, fixture or attachment mounted at its outboard end; and (3) misalignment of one or more of the machine frame members. This imparts added rigidity to the spindle in its extended positions, thereby substantially enhancing the machining accuracy and precision of the machine.

Underarm arrangement in general Prior to entering into a detailed discussion of the antisag mechanism associated with the underarm 30, it might be helpful to outline the general structural features of the underarm, its mounting, and drive, which represents one illustrative environment of such mechanism. Referring more specifically to FIGS. 2, 3, 5 and 6, it will be noted that the underarm 30 comprises in this instance a hollow rectangular structure defined by upper and lower plates 34, of relatively heavy construction and opposed side members 36, 37 which are somewhat lighter. The side members may be joined to the plates to form the underarm shell, as by welds 38, or in any other appropriate manner so as to present relatively smooth outer walls about the perimeter of the underarm. This facilitates precise guiding and supporting of the underarm in the headstock. The underarm is slidably supported in bearing surfaces provided on all four sides thereof within the headstock. The bearing surfaces are arranged to permit a minimum of clearance with respect to the underarm. Tapered gibs 40, shown in FIG. 3, are provided about the perimeter of the underarm and may be adjusted to obtain the proper clearance for a close sliding fit.

A drive arrangement is provided in the headstock 18 for extending and retracting both the spindle 26 and the underarm 30. In the present instance, drive arrangements for the spindle and underarm are interrelated to provide coincident operation of the two, although it will be appreciated that independent drive arrangements may be provided where it would be advantageous to do so. As illustrated in FIG. 3, parallel driving screws 41 and 43 powered by the headstock transmission are used to traverse the spindle and underarm. A driving nut 45, disposed upon the screw 41, is attached to the spindle 26 so that rotation of the screw 41 will result in travel of the nut 45 therealong, shifting the spindle to the left or right as indicated in FIG. 3, depending upon the direction in which the screw 41 is turned. In a like manner, a driving nut 47, secured to the upper plate 34 of the underarm 30, is mounted on the screw 43, and rotation of the screw 43 results in the translation of the underarm to the right or left as viewed in FIG. 3. The pitch of the threads of the screws 41 and 43 is such that when the screws are driven by the power source (not shown), translational movement of the spindle and underarm will be coordinated and in unison, thus providing continuous support for the spindle, regardless of its position relative to the headstock.

Anti-sag mechanism In accordance with the present invention, the underarm is constructed and arranged so as to compensate fully, throughout its range of translational movement, for deflection or droop due to its own weight, or to the weight of the tool, fixture or attachment mounted at its outboard end, or to misalignment of one or more of the machine frame members. This is accomplished through means adapted to develop appropriate internal forces within the underarm to counteract the deflection which would otherwise result from one or more of these factors. In the present instance, such means comprises an anti-sag mechanism 50 positioned within the underarm 30 and operatively connected therewith (FIGS. 2, 4A, 4B and 8).

The anti-sag mechanism 50 comprises a compensator beam 53 defined by a pair of laterally spaced upstanding flanges 55, 56 which are disposed within and longitudinally of the underarm. The upstanding flanges 55, 56 are maintained in lateral rigidity by crossbars 57 which may be fastened thereto as by screws 59.

In accomplishing the invention, the compensator beam 53 is stressed within the underarm and relative thereto in order to set up predetermined compensating reactive forces in the underarm. Controlled stressing of the beam 53 is carried out in the present instance through the novel disposition of the beam within the underarm so as to provide lever action contact between the beam and the underarm in three spaced vertical planes. These are represented in FIGS. 4A, 4B and 8 by the lines I, II and III, and the contact is such that all forces and reaction forces occurring between the beam and underarm occur substantially in those vertical planes. In the present instance, satisfactory results are obtained by providing points of contact between the beam and underarm near the ends of the underarm and at or near the ends of the beam, with a fulcrum point intermediate the above-mentioned two, but closer to one end than the other to provide a mechanical advantage.

In order to compensate for the overhanging weight of the underarm itself throughout its range of extension movement, provision is made for continuously adjusting the loading of the beam 53 as an incident to extension or retraction of the underarm. For this purpose, resort is had to a longitudinal cam mechanism 58 (see FIGS. 2, 3, 4A and 8) situated at the inboard end of the underarm 30 and beam 53. The latter comprises, in this instance, follower means mounted on the underarm and cam means connected with the beam 53.

Turning more particularly to FIGS. 2 and 4A, it will be noted that the inboard end of the underarm (the righthand end, as viewed in the drawings) is provided with a cam follower supporting frame comprising parallel side plates 60 which are fitted flush against the sides 36 and 37 of the underarm. The plates 60 are joined by a flanged base plate 62, secured by means of screws 64 to the end of the plate 35, and by an L-shaped top plate 66 rigidly secured to the member 34 of the underarm by screws 68. The side plates 66 pivotally support an upper cam follower 76 on a horizontal pivot pin 72 disposed transversely between them. The follower 70 is actually a modified bell crank comprising an arm 74, which has a roller 76 mounted on a pin 78 at its projecting end, and a pair of downwardly extending fingers 80. The latter engage in pressure contact in the vertical plane III with a correponding pair of flat abutting surfaces 83 at;

the right-hand end of the beam 53, as seen in the draw The arm 74 has a radial length several times that mgs. of each finger 80, resulting in multiplication of the force: transmitted from the roller 76 to the fingers 8t).

A second cam follower is provided in the flange plate 62 and comprises a roller 85 disposed on a pin 87 in position such that the axes of the rollers 76 and 85, respectively, are presented in a single vertical plane. The second follower is fixed with respect to the underarm and simply provides a running support for longitudinal cam 90 which actuates the follower 70.

The longitudinal cam 90 is fastened at one end to the headstock and traversed by the follower 70 as the underarm is translated. The slope of the cam 90 is mather'natically determined to 'set up counterstresses in the underarm through the medium of the beam 53 to compensate for the droop resulting from the unit weight of the underarm as it is extended. Since the weight of the extended portion of the underarm is a linear function of the amount of extension, the slope of the cam 90 is substantially linear.

In order to compensate for deflection or misalignment.

of the underarm resulting from misalignment of one or more of the machine frame members which support the underarm, the longitudinal cam 90 is provided with means for adjusting its slope. Such adjustment will tend to vary somewhat from one machine to the next due to slight variations in factors such as foundation support and guideway clearances. In effecting such compensation, the adjustment of the longitudinal cam 90 will result in the application of a reverse bend to the underarm via the compensator beam 53.

Turning again to FIGS. 2, 4A and 413, it will be perceived that the longitudinal cam 90 is constructed in two separate parts which are adjustable relative to one another. One of these parts, a base member 91 is secured to a stationary wall 93, which may conveniently comprise the rear wall of the housing of headstock 18. The base member 91 is pivoted as at 95 so that a few degrees angular movement is permitted. The bottom wall 97 of the base member is finished and hardened and rests upon the roller 85. The base member 91 is channeled as at 99 (see particularly FIGS. 2, 2A and 5), and the channel extends from the left-hand end of the base member to a point near the right-hand end of said member, as viewed in the drawings. A number of hardened pins 100 (five in this instance) traverse the channel 99 between the legs 102 flanking the channel in a line along the length thereof. The second or upper part 104 of the longitudinal cam 90 is a relatively long cam bar which rests upon, and is ad justable relative to, the base member 91.

The bar 104 is fitted with an adjustment screw 106 at the right-hand end thereof, which may be rotated by means of head 107. Thus the screw 106 may be used to move the cam bar 104 to the right or left, the screw itself being secured against axial movement as at 108. A scale 109 is mounted on the base member 91 is proximity to the end of the bar 104 and screw 106 to faciliate the making of adjustments. The cam bar 104 is formed with a plurality of notches 110, 111, 112, 113, and 114, reading from right to left along the cam member. Each such notch is fitted with a trapezoidal-shaped block 116, 117, 118, 119 and 120, each being fastened within a notch by any appropriate means, such as screws 121, such that a portion of each block below protrudes below the bar 104. Each such portion protruding below the bar 104 defines, an inclined cam surface disposed at an angle which is less than 90 from the horizontal. Each such surface is positioned opposite a pin 100 when the two parts of the cam 90 are assembled, and each surface rides on an associated piri 100 as the two parts are adjusted relatively. The angle of the inclined surfaces, which are indicated at 123, 124, 125, 126, and 127, respectively, increases from right to left so that the slope of the surface 123, for example, is relatively gentle as compared to that of the surface 127.

Thus, it will be seen from the present arrangement that as the cam bar 104 is moved relative to the base member 91, the sloping surfaces 123127, inclusive, ride successively on their associated pins 100 disposed in the channel 99 of the base member. This causes a spread ing of the cam bar 104 with respect to the base member 91, the spreading increasing progressively toward the outer end of the longitudinal cam 90. Such action gives a predetermined slope to the cam bar 104 and its top. surface 129 upon which follower roller 76 rides. The cam follower 70 is positioned to sense changes in thickness of the cam mechanism 90 in the plane of the rollers 76, 85, the thickness being varied by preadjustment of the upper portion of the cam relative to the lower.

Turning now to FIG. 8, the compensating effect of the present construction will become more apparent. Assuming that an initial setting of the relative position of the cam bar 104 and base member 91 has been established by movement of the adjusting screw 106, the surface 129 is given a predetermined slope. Now, as the underarm is extended to the left, the followers 76 and will move along opposite surfaces of the cam mechanism, and because of the preset slope which results in an increasing spread of surfaces 97 and 129, the rollers will tend to spread or move apart. This reaction to the posi tion of the longitudinal cam is transmitted through the bell crank follower 70 which tends to rotate about the pivot pin 72 to press the fingers 80 against the abutment surfaces 83 of the compensator beam 53. The downward force exerted on the abutment surfaces 83, which, it will be remembered, is at the end of the beam 53, tends to urge the beam about its intermediate pivot point indicated at on FIG. 4B which acts as a fulcrum. The pivot 135 in this case comprises a pair of aligned transverse pins 137 and corresponding bearings upon which the beam 53 is adapted to ride. A downward force exerted on the abutting surface 83 tends to rock the beam 53 in a clockwise direction about the pins 137, resulting in an upward force being exerted at the left-hand end of the beam 53 which is connected adjacent the outboard end of the underarm.

By virtue of its disposition within the underarm, the compensator beam 53 acts as a force multiplying lever to exert an increased upward force near the outboard end of the underarm to counteract the normal sagging or drooping reaction which would otherwise occur, due to the unit weight of the underarm and misalignment of the supporting machine frame members as the underarm is extended.

It will be further appreciated that as the underarm 30 is extended, the slope of the surface 129 will force the roller 76 upwardly, rotating the bell crank 70 about the pin '72 to increase the downward force on the abutting surfaces 83 of the beam 53. Thus, as the underarm is extended, the anti-sag force applied internally to the end thereof is increased proportionately in order to maintain the underarm in a stable horizontal disposition. If, upon extension of the underarm, the compensation appears to be too much or too little to offset the sag resulting from misalignment of the machine frame members, correction may be made by adjustment of the screw head 107 to vary the relative position of the cam bar 104 and base member 91 to change the slope of the surface 129 and the resultant force transmitted :to the compensator beam and underarm.

Further in keeping with the present invention, means is provided to compensate for extraordinary loads due to the weight of tools, fixtures or attachments mounted on the underarm, and which cause additional deflection or droop thereof. In the present instancethis is achieved by the use of a manually adjustable compensating arrangement situated at the outboard end of the beam 53 to modify the location of the force transmitting connection and the upward or anti-sag force transmitted to the end of the underarm.

An exemplary arrangement of the type referred to is shown in detail in FIGURES 4B, 6 and 7. In order to provide adequate room for mounting the cam arrangement 145, the left end of the beam 53 is relieved by cutting a portion thereof away, thereby providing a hat surface 147 on each of the flanges 55 and 56 thereof for receipt of a pair of cam follower brackets 149 fastened to the flanges by screws 150. Each bracket carries a cam follower 152 mounted on a pin 154, and each follower 152 abuts and defines a force transmitting connection with a polygonal shaped cam element integral with a cam member156 journaled in the side walls 36, 37 of the underarm. The cam 156 is provided with an appropriate socket 157 for engagement by a wrench or other suitable adjusting tool. In the present instance, the cam 155 is formed with a pair of identical axially spaced five-sided cam elements although it will be appreciated that such cam elements may have any convenient number of sides without departing from the invention disclosed herein. Each pair of the sides or cam surfaces 158, 153, 160, 161, and 162 is presented at a diiferent radial distance from the center 164 of the cam 156. Each such pair of sides is specially formed to compensate for the weight of a particular tool, fixture or attachment mounted on the underarm.

Adjustment of the cam 156 may be facilitated by a concentric index dial 163 surrounding the socketed end of the cam and fixed thereto, the dial being suitably marked to correspond to any given assortment of tools, fixtures or attachments to be used on the machine (FIG. 7). Thus, for example, if a milling operation is to be performed using a 500 pound milling attachment on the underarm, cam 156 may be manually rotated about its axis 164, from the underarm alone position, until a corresponding pair of sides, such as sides 158, are presented against the cam followers 152. This shifts the location of the force transmitting connection between the compensator beam 53 and the outboard end portion of the underarm 30. It also results in application of an increased increment of corrective force from the beam to the outboard end portion of the underarm of sufiicient magnitude to offset the added deflection due to the weight of the milling attachment.

Upon reflection, it will be appreciated that the anti-sag underarm arrangement described herein may also be utilized in other machine configurations with or without a headstock or spindle and whether or not the underarm is spaced from or substantially coaxial with the spindle.

We claim as our invention:

' 1. In a machine tool having a headstock, the combination comprising a headstock housing, a spindle mounted in said housing for rotation and for projected axial translation, an extensible underarm slidably mounted in said housing below and spaced from said spindle for longitudinal translation parallel to said spindle, said underarm being adapted to support a tool element adjacent the projecting end of said spindle and in driving relation thereto, a compensator beam mounted within said underarm on a fulcrum intermediate the ends thereof, said compensator beam being bodily movable with said underarm, means connecting said beam and said underarm between said fulcrum and one end of said underarm, cam and follower means interposed between said housing and the other end of said underarm, and means connecting said cam and follower means and said beam between said fulcrum and said other end of said underarm for application of a corrective. force to said beam in proportion to the extension of said underarm.

2. In a machine tool having a headstock, the combination comprising a headstock housing, a spindlemounted in said housing for rotation and for projected axial translation, said spindle being substantially horizontal, an extensible underarm slidably mounted in said housing below and spaced from said spindle for longitudinal translation parallel to said spindle, said underarm being adapted to support a tool or fixture or attachment adjacent the projecting end of said spindle and in driving relation thereto, a compensator beam mounted within said underarm on a fulcrum intermediate the ends thereof, said compensator beam being bodily movable with said underarm, means connecting said beam and said underarm between said fulcrum and one end of said underarm, a longitudinal cam fixed to said housing and disposed in telescoping relation with said underarm and said compensator beam, follower means mounted on the other end of said underarm and disposed in operative engagement with said longitudinal cam, and means connecting said follower means 0 and said beam for application of force thereto in proportion to the extension of said underarm.

3. In a machine tool having a headstock, the combination comprising a headstock housing, a spindle mounted in said housing for rotation and for projected axial translation, said spindle being substantially horizontal, an extensible underarm slidably mounted in said housing below and spaced from said spindle for longitudinal translation parallel to said spindle, said underarm being adapted to support a tool or fixture or attachment adjacent the projecting end of said spindle and in driving relation thereto,

a compensator beam mounted within said underarm on a fulcrum intermediate the ends thereof, said compensator beam being bodily movable with said underarm, means connecting said beam and said underarm between said fulcrum and one end of said underarm, a longitudinal cam fixed to said housing and disposed in telescoping relation with said underarm and said compensator beam, a follower mounted on the other end of said underarm and disposed in operative engagement with said longitudinal cam, means connecting said follower and said beam for application of force thereto in proportion to the extension of said underarm, and cam means for selectively adjusting the point of connection of said compensator beam and said underarm corresponding to particular external loads on said underarm.

4. In a machine tool having a headstock and machine frame members including a headstock housing and a supporting column, the combination comprising a spindle mounted in said housing for rotation and for projected axial translation, said spindle being substantially horizontal, an extensible underarm slidably mounted in said housing below and spaced from said spindle for longitudinal translation parallel to said spindle, said underarm being adapted to support a tool or fixture or attachment adjacent the projecting end of said spindle and in driving relation thereto, a compensator beam mounted on and bodily movable with said underarm on a fulcrum intermediate the ends thereof, means connecting said beam and said underarm between said fulcrum and one end of said underarm, a longitudinal cam fixed to said housing and disposed in telescoping relation with said underarm and said compensator beam, a follower mounted on the other end of said underarm and disposed in operative engagement with said longitudinal cam, means connecting said follower and said beam for application of force thereto in proportion to the extension of said underarm, and means for adjustably changing the slope of said longitudinal cam to introduce a correction factor for misalignment of one or more of said machine frame members.

5. In a machine tool having a headstock and machine frame members including a headstock housing and a supporting column, the combination comprising a spindle mounted in said housing for rotation and for projected axial translation, said spindle being substantially horizontal, an extensible underarm slidably mounted in said housing below and spaced from said spindle for longitudinal translation parallel to said spindle, said underarm being adapted to support a tool or fixture or attachment adjacent the projecting end of said spindle and in driving relation thereto, a compensator beam mounted on and bodily movable with said underarm on a fulcrum intermediate the ends thereof, a force transmitting connection between said beam and one end of said underarm remote from said fulcrum, a longitudinal cam fixed to said housing and disposed in telescoping relation with said underarm and said compensator beam, a follower mounted on the other end of said underarm and disposed in operative engagement with said longitudinal cam, means connecting said follower and said beam for application of force thereto in pro-portion to the extension of said underarm, means for adjustably changing the slope of said longitudinal cam to introduce a correction factor for misalignment of one or more of said machine frame members, and cam means for selectively adjusting the location of said force transmitting connection to introduce a correction factor for the weight of the tool, fixture or attachment on said underarm.

6. In a machine tool of the type which includes a column and a headstock mounted for vertical movement thereon, the combination comprising a horizontal spindle mounted in said headstock for rotation and projected axial translation, an underarm slidably mounted in said headstock and spaced from said spindle for longitudinal translation parallel to said spindle, power means for rotating said spindle and extending and retracting said spindle and said underarm with respect to said headstock, a force multiplying beam fulcrumed within said underarm, means at the headstock end of said underarm for applying a predetermined force to said beam and which includes a stationary cam having a uniformly changing slope, a cam follower for continuously sensing changes in slope of said cam as said underarm is extended and retracted from said headstock, said cam follower being adapted to transmit a change in cam slope in the form of an applied force directed to one end of said beam, said beam being adapted to multiply said applied force and transmit the same to the unsupported end of said underarm for counteracting drooping thereof, said cam comprising a base portion fixed relative to said headstock, and an upper portion adjustable relative to said base portion for varying the slope of said cam, and, accordingly, the applied force, so as to compensate for deflection of said underarm due to misalignment of one or more machine frame members.

7. In a machine tool of the type which includes a column and a headstock mounted for vertical movement thereon, the combination comprising a horizontal spindle, an underarm slidably mounted in said headstock, power transmission means for rotating said spindle and extending and retracting said spindle and said underarm with respect to said headstock, a force multiplying beam fulcrummed on said underarm, camming means for applying a force to one end of said beam in proportion to the unsupported weight of said underarm as it is extended to compensate for sag resulting from such weight, said beam being adapted to multiply and transmit the applied force to the unsupported end of said underarm, means for adjusting said camming means to compensate for changes in position of said headstock and column, and means at the end of said beam opposite said camming means disposed between said beam and said underarm for increas ing the applied force to the unsupported end of said underarm in proportion to external bending forces due to the weight of a tool, fixture or attachment mounted on the underarm.

8. In an underarm for supplying outboard support to the spindle of a machine tool, said spindle and said underarm having an inboard end and an outboard end and being translatable in parallel paths, an anti-sag mechanism for countering the tendency of said underarm to droop when extended and comprising, in combination, a beam disposed within said underarm and movable therewith, camming means at the inboard end of said underarm and engaging said beam for applying a predetermined force to the inboard end thereof, such force being applied automatically in accordance with the amount of extension of said underarm and spindle, said beam being adapted to multiply and transmit such force to the outboard end of said underarm, and a second camming means interposed between said beam and said underarm adjacent the outboard end of the latter, said second camming means being adjustable in accordance with externally applied weight loads at the outboard endof said underarm to compensate for underarm deflection due to such externally applied loads.

9. In a machine tool having an extensible underarm with an inboard end and an outboard end, an anti-sag mechanism for countering the tendency of said undearm to droop when extended and comprising, in combination,

It) a beam disposed within said underarm and movable therewith, camming means at the inboard end of said underarm and engaging said beam for applying a predetermined force to the inboard end thereof, such force being applied automatically in accordance with the amount of extension of said underarm, said beam being adapted to multiply and transmit such force to the outboard end of said underarm, and a second camming means interposed between said beam and said underarm adjacent the outboard end of the latter, said second camming means being adjustable in accordance with externally applied weight loads at the outboard end of said underarm to compensate for underarm deflection due, to such externally applied loads.

10. In a machine tool having machine frame members including a housing, the combination comprising an extensible underarm slidably mounted in said housing for longitudinal translation, said underarm being adapted to support a tool or fixture or attachment adjacent its projecting end, a compensator beam mounted on and bodily movable with said underarm on a fulcrum intermediate the ends thereof, means connecting said beam and said underarm between said fulcrum and one end of said underarm, a longitudinal cam fixed to said housing and disposed in telescoping relation with said underarm and said compensator beam, a follower mounted on the other end of said underarm and disposed in operative engagement with said longitudinal cam, means connecting said follower and said beam for application of force thereto in proportion to the extension of said underarm, and means for adjustably changing the slope of said longitudinal cam to introduce a correction factor for misalignment of one or more of said machine frame members.

11. In a machine tool adapted to perform machining operations in positions located horizontally outwardly from support structure of the machine tool, the combination comprising machine tool support structure, an elongated arm movably supported by said support structure for longitudinal translation between a retracted position and extended positions in which a machining end of the arm projects different distances from the support structure in a direction having a material horizontal component, means on said machining end of the arm adapted to support machining structure, drive means coacting with said arm to extend and retract the arm longitudinally, a gravity counteracting beam for supporting by bending moment in the beam the weight of the load on said arm and the eflective weight of the portion of the arm that projects from said support structure when the arm is fully extended, said gravity counteracting beam being disposed in generally parallel adjacent relation to said arm and having an outer end disposed near said machining end of said. arm to transmit to said machining end of the arm a force that is essentially vertical, first load bearing meansmovable with said arm and supporting said beam at a position spaced inwardly from the machining end of the arm by a distance equal to a major fraction of the length of the portion of the arm which projects from said support structure when the arm is fully extended, second load bearing means interconnecting said beam near its outer end with said arm near the machining end of the latter to transmit a vertical gravity counteracting force from the beam to the machining end of the arm, actuating means coacting with said beam to controllably apply to the beam a gravity counteracting bending moment that tends to swing said outer end of the beam upwardly about said first load bearing means to apply to said machining end of the arm a gravity counteracting lifting force that is proportional to the gravity counteracting bending moment in the beam, one of said first and second load bearing means including relative motion means for providing free movement of adjacent portions of the beam and arm relative to each other in a longitudinal direction with respect to said arm substantially to avoid transmission of horizontal force from said beam to the portion of said arm extending outwardly beyond said first load bearing means and to thereby provide that the total force transmitted by the beam to the arm outwardly of said first load bearing means is essentially vertical in direction for all degrees of gravity counteracting bending moment in the beam tending to swing the outer end of the beam upwardly; the portion of said beam extending between said first and second load bearing means being shaped and dimensioned to have sufficient strength in bending to sustain solely by bending moment in the beam, without subjecting the beam to permanent deformation, a vertical load on the outer end of the beam materially in excess of the vertical force at the outer end of said arm required to support the outer end of the arm against downward deflection when the arm is fully extended, said actuating means having a rel ationship to said beam which takes up the bending strain in the beam as an incident to operation of the actuating means to increase gravity counteracting bending moment in the beam, means interconnecting said actuating means with said arm to effect upon extension and retraction of said arm operation of said actuating means reversibly to increase and decrease in said beam extending between said first and second load bearing means the upward bending moment tending to swing the outer end of the beam upwardly; and said beam, said actuating means and said means interconnecting said actuating means with said arm being shaped and positioned in relation to each other to apply to said beam at said first load bearing means, when the arm is fully extended, a bending moment tending to swing the outer end of the beam upwardly and being substantially equal to the distance between said first and second load bearing means multiplied by the vertical force on said arm at said second load bearing means required to preclude downward displacement of the projecting end of said arm by the action of gravity.

12. In a machine tool adapted to perform machining operations in positions located horizontally outwardly from support structure of the machine tool, the combination comprising machine tool support structure, an elongated arm movably supported by said support structure for longitudinal translation between a retracted position and extended positions in which a machining end of the arm projects different distances from the support structure in a direction having a material horizontal component, means on said machining end of the arm adapted to support machining structure, drive means coacting with said arm to extend and retract the arm longitudinally; a gravity counteracting beam for transmitting, by bending moment in the beam, to the outer end of the arm a variable vertical force which sustains the outer end of the arm against downward displacement by the force of gravity on the arm and its load; said gravity counteracting beam being disposed in generally parallel adjacent relation to said arm and having an outer end disposed near said machining end of said arm, first load bearing means movable with said arm and supporting said beam at a position spaced inwardly from said machining end of the arm by a distance equal to a major fraction of the length of the portion of the arm which projects from said support structure when the arm is fully extended, second load bearing means interconnecting said beam near its outer end with said arm near the machining end of the latter to transmit a vertical gravity counteracting force from the beam to the machining end of the arm; said beam extending between said first and second load bearing means being shaped and dimensioned to have sufficient strength in bending to sustain by bending moment in the beam, without subjecting the beam to permanent deformation, a vertical load on the outer end of the beam equal to the downward force effective at the outer end of said arm, of gravity acting on the load on said arm and on the portion of the arm which projects from said support structure when the arm is fully extended; actuating means coacting with said beam to controllably apply to the beam a gravity counteracting bending moment that tends to swing said outer end of the beam upwardly about said first load bearing means so that the outer end of the beam transmits through said second load bearing means to said machining end of the arm a gravity counteracting lifting force that is proportional to the gravity counteracting bending moment in the beam, one of said first and second load bearing means including means for obviating effectively the transmission of force from said beam to said arm outwardly of said first load bearing means except for the transmission of essentially vertical lifting force from the beam to the arm, said actuating means having a relationship to said beam which takes up the bending strain in the beam as an incident to operation of the actuating means to increase gravity counteracting bending moment in the beam, means interconnecting said actuating means with said arm to effect automatically as an incident to extension and retraction of said arm operation of said actuating means reversibly to increase and decrease in said beam the upward bending moment tending to swing the outer end of the beam upwardly; and said beam, said actuating means and said means interconnecting said actuating means with said arm being shaped and positioned in relation to each other to apply to said beam a bending moment tending to swing the outer end of the beam upwardly with a force substantially equal to that required to preclude downward displacement'of the projecting end of said arm by gravity.

13. In a machine tool adapted to perform machining operations in positions located horizontally outwardly from support structure of the machine tool, the combination comprising machine tool support structure, an elongated arm movably supported by said support structure for longitudinal translation between a retracted position and extended positions in which a machining end of the arm projects different distances from the support structure in a direction having a material horizontal component, means on said machining end of the arm adapted to support machining structure, drive means coacting with said arm to extend and retract the arm longitudinally; a generally straight gravity counteracting beam for transmitting, by bending moment in the beam, to the outer end of the arm a variable vertical force which sustains the outer end of the arm against downward displacement by the force of gravity on the arm and its load; said gravity counteracting beam being disposed in generally parallel adjacent relation to saidarm and having an outer end disposed near said machining end of said arm, first load bearing means movable with said arm and coacting with a medial portion of said beam to pivotally support said beam for pivotal movement about a generally horizontal pivotal axis generally perpendicular to the arm, said pivotal axis for said beam being located medially along the length of said beam and being spaced inwardly from said machining end of the arm by a distance equal to a major fraction of the length of the portion of the arm which projects from said-support structure when the arm is fully extended, second load bearing means interconnecting said beam near its outer end with said arm near the machining end of the latter to transmit a vertical gravity counteracting force from the beam to the machining end of the arm; actuating means coacting with the inner end of said beam to controllably displace the inner end of the beam downwardly to produce in the beam a gravity counteracting bending moment that tends to swing said outer end of the beam upwardly about said pivotal axis so that the outer end of the beam transmits through said second load bearing means to said machining end ofthe arm a gravity counteracting lifting force that is generally proportional to the degree to which the inner end of the beam is displaced downwardly, one of said first and second load bearing means including relative motion means for providing free movement of adjacent portions of the arm and beam relative to each other in a longitudinal direction with respect to said arm substantially to avoid transmission of horizontal force from said beam to the portion of said arm extending outwardly beyond said first load bearing means and to thereby provide that the total force transmitted by the beam to the arm outwardly of said first load bearing means is essentially vertical in direction; said beam being shaped and dimensioned to have suflicient strength in bending to sustain by bending moment in the beam extending betweeen said actuating means and said second load bearing means, without subjecting the beam to permanent deformation, a vertical load on the outer end of the beam equal to the downward force, effective at the outer end of said arm, of gravity acting on the load on said arm and on the portion of the arm which projects from said support structure when the arm is fully extended; means interconnecting said actuating means with said arm to effect automatically as an incident to extension and retraction of said arm operation of said actuating means reversibly to increase and decrease the extent of downward displacement of the inner end of said beam; said actuating means and said means interconnecting said actuating means with said arm being shaped and positioned in relation to each other to displace the inner end of the beam downwardly to a degree which tends to swing the outer end of the beam upwardly with a force generally equal to that required to preclude downward displacement of the machining end of said arm by gravity.

14. In a machine tool adapted to perform machining operations in positions located horizontally outwardly from support structure of the machine tool, the combination comprising machine tool support structure, an elongated arm movably supported by said support structure for longitudinal translation between a retracted position and extended positions in which a machining end of the arm projects different distances from the support structure in a direction having a material horizontal component, means on said machining end of the arm adapted to support machining structure, drive means coacting with said arm to extend and retract the arm longitudinally, a gravity counteracting beam for supporting by bending moment in the beam the weight of the load on said arm and the effective weight of the portion of the arm that projects from said support structure when the arm is extended,

said gravity counteracting beam being disposed in generallly parallel adjacent relation to said arm and having an outer end disposed near said machining end of said arm to transmit to said machining end of the arm a force that is essentially vertical, first load bearing means movable with said arm and supporting said beam at a position spaced inwardly from the machining end of the arm by a distance equal to a major fraction of the length of the portion of the arm which projects from said support structure when the arm is fully extended, second load bearing means interconnecting said beam near its outer end with said arm near the machining end of the latter to transmit a vertical gravity counteracting force from the beam to the machining end of the arm, actuating means coacting with said beam to controllably apply to the beam a gravity counteracting bending moment that tends to swing said outer end of the beam upwardly about said first load bearing means to apply to said machining end of the arm a gravity counteracting lifting force that is proportional to the gravity counteracting bending moment in the beam; the portion of said beam extending between said first and second load bearing means being shaped and dimensioned to have suflicient strength in bending to sustain solely by bending moment in the beam, without subjecting the beam to permanent deformation, a vertical load on the outer end of the beam materially in excess of the vertical force at the outer end of said arm required to support the outer end or the arm against downward deflection when the arm is fully extended; said actuating means having a relationship to said beam which takes up the bending strain in the beam as an incident to operation of the actuating means to increase gravity counteracting bending moment in the beam, means interconnecting said actuating means with said arm to efiect upon extension and retraction of said arm operation 'of said actuating means reversibly to increase and decrease in said beam extending between said first and second load bearing means the upward bending moment tending to swing the outer end of the beam upwardly; and said beam, said actuating means and said means interconnecting said actuating means with said arm being shaped and positioned in relation to each other to apply to said beam at said first load bearing means, when the arm is fully extended, a bending moment tending to Swing the outer end of the beam upwardly and being substantially equal to the distance between said first and second load bearing means multiplied by a vertical force on said arm at said second load bearing means generally equal to the downward force, effective at said second load bearing means, of gravity acting on the load on said arm and on the portion of the arm projecting from said support structure.

15. In a machine tool adapted to perform machining operations in positions located horizontally outwardly from support Structure of the machine tool, the combination comprising machine tool support structure, a hollow elongated arm movably supported by said support structure for longitudinal translation between a retracted position and extended positions in which a machining end of the arm projects difierent distances from the support structure in a direction having a material horizontal component, means on said machining end of the arm adapted to support machining structure, drive means coacting with said arm to extend and retract the arm longitudinally; a generally straight gravity counteracting beam for transmitting, by bending moment in the beam, to the outer end of the arm a variable vertical force which sustains the outer end of the arm against downward displacement by the force of gravity on the arm and its load; said gravity counteracting beam being disposed within said arm in generally parallel relation thereto and having an outer end disposed near said machining end of said arm, first load bearing means on said arm coacting with a medial portion of said beam to pivotally support said beam for pivotal movement about a generally horizontal pivotal axis generally perpendicular to the arm, said pivotal axis for said beam being located medially along the length of said beam and being spaced inwardly from said machining end of the arm by a distance equal to a major fraction of the length of the portion of the arm which projects from said support structure when the arm is fully extended, second load bearing means interconnecting said beam near its outer end with said arm near the machining end of the latter to transmit a vertical gravity counteracting force from the beam to the machining end of the arm; actuating means coacting with the inner end of said beam to controllably displace the inner end of the beam downwardly to produce in the beam a gravity counteracting bending moment that tends to swing said outer end of the beam upwardly about said pivotal axis so that the outer end of the beam transmits through said second load caring means to said machining end of the arm a gravity counteracting lifting force that is generally proportional to the degree to which the inner end of the beam is displaced downwardly, said s-econd load bearing means including means defining on said beam and arm respectively abutment surfaces slidably engaging each other to transmit vertical lifting force from the beam to the arm and at the same time allow free sliding movement of the outer ends of said beam and said arm in relation to each other in a horizontal direction generally parallel to said beam to avoid the transmission of horizontal force of any substantial degree from the beam to the arm outwardly of said first load bearing means; said beam being shaped and dimensioned to have sufiicient strength in bending to susmin by bending moment in the beam extending between said actuating means and said second load bearing means, without subjecting the beam to permanent deformation, a vertical load on the outer end of the beam equal to the downward force, effective at the outer end of said arm, of gravity acting on the load on said arm and on the portion of the arm which projects from said support structure when the arm is fully extended; means interconnecting said actuating means with said arm to eiTect automatically as an incident to extension and retraction of said arm operation of said actuating means reversibly to increase and decrease the extent of downward displacement of the inner end of said beam; and said beam, said actuating means and said means interconnecting said actuating means with said arm being shaped and positioned in relation to each other to displace the inner end of the beam downwardly to a degree which tends to swing the outer end of the beam upwardly with a force generally equal to that required to preclude downward displacement of the machining end of said arm by gravity.

16. In a machine tool adapted to perform machining operations in positions located horizontally outwardly from support structure of the machine tool, the combination comprising machine tool support structure, an elongated arm movably supported by said support structure for longitudinal translation between a retracted position and extended positions in which a machining end of the arm projects different distances from the support structure in a direction having a material horizontal component, means on said machining end of the arm adapted to support machining structure, drive means coacting with said arm to extend and retract the arm longitudinally, a gravity counteracting beam for supporting by bending moment in the beam the weight of the load on said arm and the effective weight of the portion of the arm that projects from said support structure when the arm is extended, said gravity counteracting beam being disposed in generally parallel adjacent relation to said arm and having an outer end disposed near said machining end of said arm to transmit to said machining end of the arm a force that is essentially vertical, first load bearing means movable with said arm and supporting said beam at a position spaced inwardly from the machining end of the arm by a distance equal to a major fraction of the length of the portion of the arm which projects from said support structure when the arm is fully extended, second load bearing means 16 interconncctingsaid beam near its outer end with said arm near the machining end of the latter to transmit a vertical gravity counteracting force from the beam to the machining end of the arm, actuating means coacting with said beam to controllably apply to the beam a gravity counteracting bending moment that tends to swing said out-er end of the beam upwardly about said first load bearing means to apply to said machining end of the arm a gravity counteracting lifting force that is proportional to the gravity counteracting bending moment in the beam; the portion of said beam extending between said first and second load bearing means being shaped and dimensioned to have suffiicent strength in bending to sustain solely by bending moment in the beam, without subjecting the beam to permanentdeformation, a vertical load on the outer end of the beam materially in excess of the vertical force at the outer end of said arm required to support the outer end of the arm against downward deflection when the arm is fully extended; said arm, said beam and said first and second load bearing means including means for obviating the transmission of material horizontal force from said beam to said arm outwardly of said first load bearing means for all degrees of bending moment applied to said arm by said actuating means to urge the outer end of the beam upwardly, means interconnecting said actuating means with said arm to effect upon extension and retraction of said arm operation of said actuating means reversibly to increase and decrease in said beam extending between said first and second load bearing means the upward bending moment tending to swing the outer end of the beam upwardly; and adjustable preloadin g means for applying to said beam when said arm is fully retracted a residual bending moment tending to urge the outer end of the beam upwardly with an arm load lifting force that is adjustable by adjustment of the preloading means.

References Cited by the Examiner UNITED STATES PATENTS 2,890,629 6/1959 Schurger et al 16 2,912,905 11/1959 Berthiez 90-16 3,097,568 7/1963 Kampmeier 77-3 X WILLIAM W. DYER, 111., Primary Examiner.

LEON PEAR, Examiner. 

1. IN A MACHINE TOOL HAVING A HEADSTOCK, THE COMBINATION COMPRISING A HEADSTOCK HOUSING, A SPINDLE MOUNTED IN SAID HOUSING FOR ROTATION AND FOR PROJECTED AXIAL TRANSLATION, AN EXTENSIBLE UNDERARM SLIDABLY MOUNTED IN SAID HOUSING BELOW AND SPACED FROM SAID SPINDLE FOR LONGITUDINAL TRANSLATION PARALLEL TO SAID SPINDLE, SAID UNDERARM BEING ADAPTED TO SUPPORT A TOOL ELEMENT ADJACENT THE PROJECTING END OF SAID SPINDLE AND IN DRIVING RELATION THERETO, A COMPENSATOR BEAM MOUNTED WITHIN SAID UNDERARM ON A FULCRUM INTERMEDIATE THE ENDS THEREOF, SAID COMPENSATOR BEAM BEING BODILY MOVABLE WITH SAID UNDERARM, MEANS CONNECTING SAID BEAM AND SAID UNDERARM BETWEEN 